Bai Xian Pi (Cortex of Chinese Dittany Root)

Chinese Herb Actions

Chinese Herb Dosage

• What is the typical dosage of Bai Xian Pi?

  Roughly 6–9 g in decoction — the part used is the dried root bark (cortex), which is stripped from the root, dried, and cut into curled strips or rolls before use. It is also used externally: decocted and applied as a wash, soak, or compress for itchy, weeping, or ulcerated skin, where larger quantities of raw herb are prepared because the liquid is not swallowed.

  • Part used — root bark only. The woody core of the root is discarded; the medicinal material is the peeled bark layer.
  • Internal — decocted with other herbs at the range above.
  • External — prepared as a wash or soak for the affected area, one of its most characteristic traditional applications.

  Because of the liver-injury reports summarized in the toxicity section below, this herb is one where the professional-supervision point is more than a formality: it is not a self-prescribing herb.

  Source: Sacred Lotus sources & references, cross-referenced against multiple online sources (standard materia medica ranges and preparation notes). Reference only — not a prescription.

Chinese Herb Contraindications & Cautions

• Are there cautions for Bai Xian Pi?

  Bai Xian Pi is bitter and cold, so it is traditionally avoided where there is cold from Spleen and Stomach deficiency — poor appetite, loose stools, and a cold, weak digestion, all of which a cold, draining herb can worsen. Beyond that traditional caution, this herb carries a documented liver-injury signal in the modern clinical literature that is described in full in the toxicity section below.

  • Traditional contraindication — cold from deficiency of the Spleen and Stomach; not suited to deficiency patterns without damp-heat.
  • Documented liver-injury reports (reference note) — Dictamnus dasycarpus appears repeatedly among herbs named in published herb-induced liver injury case series in Korea, China, and the United Kingdom, both as a single herb and as an ingredient of multi-herb products. See the toxicity section for the specifics.
  • Professional supervision — for the reason above, this is a herb used within a practitioner-managed formula rather than self-selected, and anyone with existing liver disease or taking hepatically metabolised medicines has an additional reason to work with a qualified practitioner.

  Source: Sacred Lotus sources & references (traditional contraindication); liver-injury literature cited in the toxicity section. Neutral reference disclosure — not monitoring or dosing advice.

Chinese Herb Toxicity & Overdose

• Is Bai Xian Pi toxic to the liver?

  Bai Xian Pi is not classified as a toxic herb in the traditional materia medica, but it is one of the relatively few Chinese herbs with a repeatedly documented herb-induced liver injury (HILI) signal in the published clinical literature — reported from Korea, China, and the United Kingdom, in both single-herb and multi-herb contexts. This is stated here as a matter of record, not as a prediction about any individual.

  What is actually documented:

  • Korea, single-herb decoction (2008) — four cases of toxic hepatitis after drinking a decoction made by boiling Dictamnus dasycarpus root, including a mother and daughter. The reported course was benign, resolving within about a month after the herb was stopped.
  • Korea, systematic review (2015) — in a systematic review of herb-induced liver injury cases reported in Korea (97 cases across 21 herbal preparations), Dictamnus dasycarpus was the single most frequently implicated agent, accounting for roughly 37% of cases.
  • United Kingdom / European literature review (2002) — a review of the English-language literature on hepatitis associated with Chinese herbs, published in a European gastroenterology and hepatology journal, identified two products as recurring: Jin Bu Huan (11 patients) and Dictamnus dasycarpus, which had been taken by six patients — including both of the fatal cases in the reviewed series.
  • China, single case (2017) — a reported case of drug-induced liver injury attributed to D. dasycarpus powder taken at 15 g per day.
  • Multi-herb products — liver damage has also been investigated in proprietary multi-ingredient preparations that contain Bai Xian Pi, such as Keyin Pills, with both clinical cases and experimental follow-up reported.

  Why causality is hard to establish. The 2002 European review states the problem plainly: these products are frequently mixtures that may also contain adulterants, so conclusive attribution to any one ingredient is difficult. The same limitation applies across most of this literature — multi-herb formulas, variable material quality, co-administered medicines, and retrospective reporting all sit between an observed injury and a named herb. The pattern described in the mechanistic literature is idiosyncratic rather than dose-predictable, meaning it is not the kind of effect that a simple dose ceiling would describe.

  What laboratory work suggests about mechanism. Experimental studies have proposed that the alkaloid isomaculosidine contributes to idiosyncratic liver injury by driving mitochondrial reactive oxygen species and activating the NLRP3 inflammasome; other work has examined cytochrome P450-mediated bioactivation of constituents including fraxinellone, and reported oxidative-stress markers such as reduced glutathione peroxidase. These are laboratory and animal findings offered as mechanistic context, not clinical predictions.

  Sources: PMID 18617768 (four cases of toxic hepatitis after D. dasycarpus decoction, Korea); PMID 26165727 (systematic review of herb-induced liver injury in Korea); PMID 11984156 (hepatitis associated with Chinese herbs, Eur J Gastroenterol Hepatol 2002); PMID 28952271 (clinical case attributed to Dictamni Cortex powder); PMID 33350277 (Keyin Pills liver damage, clinical cases and experimental evaluation); PMID 37598766 (isomaculosidine and NLRP3 inflammasome activation); PMID 32484342 (cytochrome P450-mediated bioactivation); PMID 37446707 (mechanism of Dictamnus-induced hepatotoxicity); PMID 34874447 (review of traditional uses, phytochemistry, pharmacology and toxicology). Neutral reference record of published findings — not a safety assessment of any product and not medical advice.

Herb-Drug Interactions

• Does Bai Xian Pi interact with medications?

  No well-established clinical herb–drug interaction has been documented for Bai Xian Pi. What exists instead is indirect: laboratory work reports that constituents of Dictamnus dasycarpus undergo cytochrome P450-mediated bioactivation, with CYP1A2 among the enzymes implicated in the metabolic pathways studied in relation to liver injury. That is a preclinical mechanistic finding, not a demonstrated clinical interaction, and it should not be read as a specific drug-pairing warning.

  Given the liver-injury literature recorded above, practitioner awareness is reasonable where a patient is already taking hepatically metabolised medicines or has existing liver disease. This is a precautionary, practitioner-level consideration rather than an established interaction. (Flagged for practitioner confirmation — absence of documented interactions is not proof of safety.)

  Source: PMID 32484342 (cytochrome P450-mediated bioactivation); PMID 37446707 (hepatotoxicity mechanism, CYP1A2 among implicated pathways). Preclinical context only.

Western / Biomedical Research

Chinese Herb Clinical Studies & Research

Provided as research context — a summary of published biomedical study, not a therapeutic or medical claim.

• Is there modern research on Bai Xian Pi (Dictamnus dasycarpus)?

  Yes — a substantial phytochemical and preclinical literature, and an unusually well-developed toxicology literature for a herb of this profile. A 2021 review reports that the root bark contains more than 200 identified compounds, dominated by alkaloids and their glycosides, terpenoids (including limonoids such as fraxinellone and obacunone), and phenylpropanoids. Reported laboratory activities include anti-inflammatory, cardiovascular-protective and anti-cancer effects, alongside the hepatotoxicity findings.

  • Chemistry and pharmacology (review) — the 2021 review in a pharmacy and pharmacology journal covers traditional uses, phytochemistry, pharmacology and toxicology together, and notes modern clinical application in China for skin inflammation, eczema, rubella-type eruptions, rheumatic complaints and gynaecological inflammation.
  • Anti-inflammatory activity — reported in laboratory and animal models, consistent with the herb’s traditional damp-heat skin indications, though this is mechanism research and not clinical proof of effect.
  • Hepatotoxicity mechanism — the most active research thread. Work published in 2023 and 2024 has examined how extract constituents produce liver injury, identifying isomaculosidine as activating the NLRP3 inflammasome via mitochondrial reactive oxygen species and reporting oxidative-stress changes including decreased glutathione peroxidase. See the toxicity section for the clinical side of this literature.
  • Fraxinellone — a characteristic limonoid of the plant, studied both for immunological activity (including a 2009 report on T-cell apoptosis in a hepatitis model) and as a substrate in the bioactivation work above. The same compound appearing on both sides of that literature is a reminder that constituent-level findings do not translate directly into whole-herb safety or efficacy conclusions.

  Rigorous single-herb human clinical trials for Bai Xian Pi are not available; the human data that does exist is largely adverse-event reporting.

  Sources: PMID 34874447 (traditional uses, phytochemistry, pharmacology and toxicology review, J Pharm Pharmacol 2021); PMID 37446707 (hepatotoxicity mechanism, Molecules 2023); PMID 37598766 (isomaculosidine and inflammasome activation, J Ethnopharmacol 2024); PMID 32484342 (CYP450-mediated bioactivation, Chem Res Toxicol 2020); PMID 19428326 (fraxinellone and T-cell apoptosis, Biochem Pharmacol 2009). Research context, not a therapeutic claim.

Chinese Herb Notes

• What plant is Bai Xian Pi, and how is it different from Ku Shen and Di Fu Zi?

  Bai Xian Pi is the root bark of Dictamnus dasycarpus Turcz., a perennial in the citrus family (Rutaceae) — not an aromatic mint, despite the English name “dittany.” The name is a long-standing source of confusion, and the genus itself is small: Plants of the World Online currently accepts only three species, D. dasycarpus, D. albus (the European “white dittany” or burning bush), and D. hispanicus.

  • Not dittany of Crete — Origanum dictamnus, the Cretan culinary and folk herb also called dittany, is in the mint family (Lamiaceae) and is botanically unrelated to Dictamnus. The shared English word reflects an old naming overlap in classical literature, not a shared plant.
  • Not the same as D. albus — some Western literature discusses Dictamnus albus under the same common name; the Chinese medicinal is specifically D. dasycarpus, and material identity matters when reading source studies.

  How it differs from its close neighbours in the itching/skin group:

  • vs Ku Shen (Sophora root) — both are bitter and cold and both dry damp and stop itching; Ku Shen is the stronger damp-heat drainer, is also used for damp-heat dysentery and damp-heat urinary patterns, and is markedly more bitter and harsher on digestion. Bai Xian Pi is more specifically directed at the skin and adds a wind-expelling quality.
  • vs Di Fu Zi (Kochia fruit) — Di Fu Zi clears damp-heat mainly by promoting urination and is a gentler, more diuretic anti-itch herb; Bai Xian Pi works more directly on the skin surface and on toxic-heat lesions.
  • vs She Chuang Zi (Cnidium fruit) — She Chuang Zi is acrid, bitter and warm, used for cold-damp itching and parasitic skin lesions; Bai Xian Pi is cold and belongs to hot, damp presentations. They are not interchangeable, and the temperature is the deciding factor.

  Common combinations: traditionally paired with Ku Shen and Di Fu Zi for damp-heat itching (internally and as an external wash), and with Bai Ji Li for wind-type moving itch. (Traditional combination context, not treatment advice.)

  Source: Sacred Lotus sources & references (herb identity and differentiation); botanical placement cross-referenced against multiple online sources and Plants of the World Online.